With the continuous development of the Thin Film Transistor Liquid Crystal Display (TFT-LCD) technology, TFT display devices based on the Low Temperature Poly-silicon (LTPS) technology and having the advantages of low power consumption, high resolution, fast response speed and high aperture ratio gradually become the mainstream display and have been widely used in various electronic devices, such as a liquid crystal television, a smart phone, a tablet PC and a digital camera and other digital electronic devices.
However, in high resolution products such as the TFT display devices based on the LTPS technology, the ever increasing of the resolution and the aperture ratio of the products will cause the pixel pitch of the array substrate of the LTPS TFT display device to become even smaller, which will in turn make the storage capacitance of the array substrate smaller. With the same drain current, smaller storage capacitance of the LTPS TFT array substrate will make the voltage holding ratio of the pixel lower, which will further cause defects such as flicker, thereby severely reducing the quality of the array substrate or the high resolution products such as the TFT display device. Therefore, a problem to be solved urgently in the industry is to increase the storage capacitance while not affecting the aperture ratio of the array substrate.